On Thursday, September 17, the Volcano Alert Level and Aviation Color Code for Mauna Loa was elevated to Advisory/Yellow based on long-term trends in both earthquake and deformation monitoring data.
Mauna Loa is not erupting. A swarm of approximately 20 small earthquakes occurred on Mauna Loa’s West Flank at a depth of approximately 8 km (5 mi). Earthquakes occurred beneath Mauna Loa’s upper Southwest Rift Zone at rates greater than background but below earthquake rates recorded over the summer of 2015. Deformation data remain consistent with inflation of magma reservoirs beneath Mauna Loa’s summit and upper Southwest Rift Zone.
March 25, 1984 : Following 18 months of increased seismicity and summit inflation, Mauna Loa’s most recent eruption began at 1:30 a.m. HST, when a fissure (left) opened in Moku??weoweo, the volcano’s summit caldera. By 4:00 a.m., the eruption had migrated into Mauna Loa’s upper east rift zone, where active fissures eventually reached the 9,300-ft elevation. Fast-moving ?a?? flows advanced downslope, and in a matter of days, lava was within 6 km (4 miles) of Hilo city limits. Fortunately, the eruption ended on April 15 before lava reached Hilo.
November 06, 2015. Mauna Loa , Hawaï:
19°28’30 » N 155°36’29 » W,
Summit Elevation 13681 ft (4170 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
Source : HVO
Photo : R.W. Decker le 28 Mars 1984.